Age of Mineralization and Mine Dykes at Copper Mountain Alkaline Copper-Gold-Silver Porphyry Deposit (NTS 092H/07), South-Central British Columbia

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1 Age of Mineralization and Mine Dykes at Copper Mountain Alkaline Copper-Gold-Silver Porphyry Deposit (NTS 092H/07), South-Central British Columbia by M.G. Mihalynuk, J. Logan, R.M. Friedman 1 and V.A. Preto 2 KEYWORDS: Cop per Moun tain, alkalic por phyry, Cu-Au- Ag de posit, min er al iza tion, al ter ation, geo chron ol ogy, iso - to pic age, U-Pb zir con, U-Pb ti tan ite, 40 Ar/ 39 Ar, Quesnel Arc INTRODUCTION Un der ground mass min ing tech niques have en abled prof it able ex trac tion of the deep por tions of por phyry de - pos its at minesites world wide. Of ten con sid ered a rel a - tively new in no va tion, block cav ing was orig i nally de vel - oped for cop per min ing in Utah in 1906 (Barger and Schurr, 1944). Ex am ples of block cave min ing of cop per por phyry de pos its in clude the re cently de com mis sioned San Manuel Cu mine in Ar i zona, and the cur rently ac tive alkalic Cu-Au- Ag Ridgeway de posit in New South Wales, Aus tra lia. Prof - it able un der ground min ing of large ton nage, low-grade de - pos its com bined with the re cent strength in metal com mod - ity prices has prompted deep ex plo ra tion of por phyry de pos its in Brit ish Co lum bia, es pe cially within the pro lific Quesnel terrane (Fig ure 1). For ex am ple, in the Iron Mask batholith near Kamloops, New Gold Inc. has out lined 44.4 mil lion tonnes at a grade of 0.98% Cu, 0.72 g/t Au and 2.27 g/t Ag (New Gold Inc., 2007) be neath the for mer Afton pit and has started de vel op ment. Cop per Moun tain Min ing Cor po ra tion has sim i larly dem on strated the po ten - tial for subsurface ex ten sions to min er al iza tion that was ex - tracted from open pits at Copper Mountain, about 15 km south of Princeton, in south-central BC (Figure 2). In 2009, the com pany re ported a re source of mil - lion tonnes grad ing 0.311% Cu (0.15% Cu cut-off; O Rourke, 2008) ad ja cent to, and be neath, the pro posed super pit (Fig ure 3; Holbek, 2009). Cur rent plans are to ex tract mil lion tonnes at 0.361% Cu from the super pit (Chance et al., 2009). This re source of more than 1 bil - lion ki lo grams Cu adds sig nif i cantly to his tor i cal pro duc - tion be tween 1908 and 1996 of ~650 mil lion ki lo grams of Cu, nearly 16 mil lion grams Au and over 648 mil lion grams Ag (BC Geo log i cal Sur vey, 2009; MINFILE 092HSE001). In ad di tion, largely un tested magnetotelluric tar gets ex tend 1 Pa cific Cen tre for Iso to pic and Geo chem i cal Re search, The Uni ver sity of Brit ish Co lum bia, Van cou ver, BC 2 Preto Geological Inc., Sooke, BC This publication is also available, free of charge, as colour digital files in Adobe Acrobat PDF format from the BC Ministry of Energy, Mines and Petroleum Resources website at logue/fieldwork/pages/default.aspx. Fig ure 1. Lo ca tion of the Cop per Moun tain area south of Prince - ton, south-cen tral Brit ish Co lum bia. The area cov ered by Fig ure 2 is shown on top of the south ern part of the Prince ton town sym bol m be low the low est planned super pit levels (Holbek, 2007, 2009). Large cap i tal ex pen di tures are re quired for deep ex plo - ra tion and de vel op ment, so a clear and ac cu rate ex plo ra tion model is par tic u larly de sir able. To this end, we ini ti ated a geo chron ol ogi cal in ves ti ga tion of the min er al iz ing sys tem at Cop per Moun tain in Our prin ci pal ob jec tive was to test the as ser tion that min er al iza tion at Cop per Moun tain was co eval with the em place ment of the Lost Horse In tru - sions of the Cop per Moun tain in tru sive suite (e.g., Fig ure 4; Preto, 1972). How ever, ex ist ing geochronometric de ter mi - na tions place the age of min er al iza tion in the Early Ju ras sic Geo log i cal Field work 2009, Pa per

2 (192 ±16 Ma and 198 ±14 Ma; Breitsprecher and Morten - sen, 2004; re cal cu lated from Preto, 1972 and Farquharson and Stipp, 1969, re spec tively), while the best crys tal li za - tion age data on phases of the min er al ized Cop per Moun - tain suite in tru sive rocks place them in the Late Tri as sic (Fig ure 4; Mortensen et al., 1995; / 0.5 Ma, ±2.1 Ma and 204 ±6 Ma). Based on these data, and in con sid er ation of their full er ror lim its, be tween 14 and 33 m.y. (me dian, 7 m.y.) elapsed be tween in tru sion and min er al iza tion of the Cop per Moun tain stock. Even with - out con sid er ing er ror en ve lopes, the means of these datasets sug gest that 7 m.y. elapsed, which is far greater than is typ i cal for the main min er al iz ing event in porphyry deposits (McInnis et al., 2005) and raises the question of a separate, younger mineralizing intrusion. Geochronometric data from var i ous work ers have been com bined to gether with new data as part of an in ves ti - ga tion of Me so zoic cop per por phyry de pos its in BC un der the di rec tion of J. Lo gan (Lo gan and Mihalynuk, 2005a, b; Lo gan and Bath, 2006; Lo gan et al., 2007). This work has shown that in creased geochronometric pre ci sion on in tru - sive and min er al iz ing events re veals them to be co eval, within the res o lu tion of the geochronometric tech nique ap - plied. Ad di tion ally, the new data show that, with a few no - ta ble ex cep tions, all alkalic cop per por phyry de pos its in the Ca na dian Cor dil lera are part of a met al lo gen ic ep och in the lat est Tri as sic (to gether with nu mer ous calcalkalic de pos - its, such as High land Val ley; e.g., Ash et al., 2007). Herein we af firm both the ad di tion of the Cop per Moun tain alkalic por phyry to this ep och and the orig i nal as ser tion of Preto (1972), that in tru sion and mineralizing events are es sen - tially synchronous at Copper Mountain. LOCATION AND GEOLOGICAL SETTING Fig ure 2. Re gional geo log i cal map of the Cop per Moun tain area, south-cen tral Brit ish Co lum bia, in cor po rat ing map - ping by Preto (1972) and com pi la tions by Preto et al. (2004) and Massey et al. (2005). Cop per Moun tain is lo cated within the Quesnel Arc (Fig ure 1), a crustal terrane that accreted to an ces tral North Amer ica (ANA) or a crustal rib bon that lay ad ja cent to ANA in Early Ju ras sic time (ca. 186 Ma; Nixon et al., 1993). Subduction of an cient Pa cific Ocean crust to form the proto-quesnel and con joined Stikine arcs is be lieved to have be gun in the De vo nian (e.g., Brown et al., 1996; Mihalynuk, 1999; Lo gan and Koyanagi, 2000). Arc growth con tin ued spo rad i cally with a sig nif i cant pulse in the Late Tri as sic. Near the end of this mag matic pulse, a pro lific met al lo gen ic event is man i fest as a chain of alkalic Cu Au±Ag Mo por phyry de pos its along the arc axes. In tru - sions al lied with min er al iza tion at Cop per Moun tain were rec og nized by Preto (1972, 1979) as part of this wellendowed magmatic suite. Min er al iza tion at Cop per Moun tain is mainly fo cused at the mar gins and be tween the polyphase Cop per Moun - tain stock (to the south) and the Lost Horse In tru sions (to the north). In ter ven ing coun try rocks that host the bulk of the min er al iza tion lo cally dis play protolith tex tures of andesitic to ba saltic lapilli tuff and brec cia be long ing to the Late Tri as sic Nicola Group. In tense hy dro ther mal al ter - ation of these rocks gen er ally dis plays the fol low ing petro - gen esis: 1) bi o tite flood ing 2) ex ten sive al bite-epidote metasomatism 3) K-feld spar and scapolite vein ing 164 British Columbia Geological Survey

3 SAMPLES FOR AGE DETERMINATION Four samples were selected for isotopic age determination. Two samples from mineralized veins that contain medium-grained crystals of titanite were collected for U-Pb determination. Because of the relatively high closure temperature for lead diffusion in titanite at oC (Scott and St-Onge, 1995), relatively straightforward iso to pic age de ter mi na tions were an tic i pated from the mineralization in these two vein samples. In addition, coarse-grained euhedral biotite was extracted from an archival specimen of museumquality massive bornite-chalcopyrite-biotite from the Big Lead to provide a 40Ar/39Ar cooling age on mineralization from a spectacular glory hole (now mined out). The fourth sample, a relatively unaltered representative sample of the Mine Dyke swarm (Figures 3, 5), was collected to date the late, crosscutting intrusions. We are not aware of any published crystallization age for the Mine Dyke swarm; existing ages are cooling ages, mainly KAr and fission-track determinations. Titanite-Bearing Veins Ti tan ite oc curs in dom i nantly southtrending, planar sets of K-feldspar veins. Vein mineralogy includes coarse, chloritized biotite, mal a chite-stained bornite and chal co py rite, epidote and titanite (Figure 6). White alteration envelopes are interpreted as albite; no bladed scapolite was observed. These veins were sampled at the margin of the Copper Mountain stock (MMI ) along the haul road south of Pit 1 (Figure 3) and midway between the Copper Mountain stock and the main body of Lost Horse Intrusions, on the north rim of Pit 2 (MMI ). They probably belong to the ore fractures reported by Preto (1972). Where the veins of pegmatitic biotite K-feldspar copper sulphides, called ore fractures, thickened to 30 cm or more, they were historically exploited by miners from glory holes. One especially rich glory hole, known as the Big Lead, was located in what is now the central part of Pit 3. Figure 3. Locations of geochronological samples collected as part of this study (large symbols) and those collected previously by other authors (smaller sym bols) as re ported in the da ta base com piled by Breitsprecher and Mortensen (2004), Copper Mountain area, south-central British Columbia. Geological contacts and underlying imagery are adapted from Preto et al. (2004). The proposed super pit outline is from Chance et al. (2009). Values on the map are in Ma. Big Lead Massive Bornite-Biotite Massive bornite chalcopyrite biotite±k-feldspar of the Big Lead was sampled by V.A. Preto in The sample was taken from the subsidence area over shallow stopes and glory holes, which was located near what is now the middle of Pit 3 (see Plate XIII in Preto [1972] for a historical perspective). This archival sample contains beautiful, euhedral booklets of coarse, vitreous biotite within massive copper sulphide. Such textural equilibrium suggests simultaneous growth of the idiomorphic biotite crystals and chalcopyrite from a magmatic-hydrothermal fluid. Idiomorphic biotite enclosed in bornite is reported at other high-grade porphyry deposits such as Grasberg, where they are interpreted as coarse-grained replacements of mafic phenocrysts (Pollard et al., 2005). Geological Fieldwork 2009, Paper Mine Dyke Swarm The Mine Dykes are white to yellow-orange weathering, blocky to flaggy and relatively recessive (Figure 5). They dip steeply and anastomose, generally conforming to a strong north-northeast trend with a few orthogonal exceptions (Fig ures 2, 3. 5). Preto (1972) re ported their compositional range as trachyte to rhyo lite. Mediumgrained, grey quartz eyes are con spicu ous (7%), and coarse-grained probable K-feldspar relicts are replaced by greasy green clay. Matrix material is a bleached, finegrained aplite with ~1% magnetite and traces of pyrite. In general, the dikes are strongly clay- and carbonate-altered and only ghosts of former feldspar phenocrysts remain. 165

4 U-PB GEOCHRONOLOGY METHODS Sam ple prep a ra tion and an a lyt i cal work for both the U- Pb and the 40 Ar/ 39 Ar iso to pic ages pre sented herein was con ducted at the Pa cific Cen tre for Iso to pic and Geo chem i - cal Re search (PCIGR) at the De part ment of Earth and Ocean Sci ences, The Uni ver sity of British Columbia. Ti tan ite was hand picked from sam ples MMI and Picked sam ples were mi cro scop i cally eval u ated to en sure pu rity (Fig ure 7). Pink, brown and green ish grain frag ments of mod er ate clar ity were se lected for anal y sis. Ti tan ite sam ple aliquots an a lyzed are shown in Fig ure 7. Ura nium-lead iso to pic age de ter mi na tions were ob tained by ther mal ion iza tion mass spec tros copy (U-Pb ID-TIMS) with re sults listed in Table 1 and plotted in Figure 8. Zir con was sep a rated from the Mine Dyke sam ple MMI us ing stan dard min eral sep a ra tion tech niques (crush ing, grind ing, Wilfley wet shaker ta ble, heavy liq uids and mag netic sep a ra tion), fol lowed by hand pick ing. Airabraded sin gle zir con grains were an a lyzed (Fig ure 7). Ura - nium-lead iso to pic age de ter mi na tions were ob tained by U- Pb ID-TIMS with re sults listed in Ta ble 2 and plot ted in Fig ure 9. De tails of both the min eral sep a ra tion and an a lyt i - cal tech niques are pre sented in Lo gan et al. (2007). U-PB GEOCHRONOLOGY RESULTS All data over lap con cordia at the 2 con fi dence level and quoted ages are based on Lud wig con cordia in ter pre ta - tions (Fig ures 8, 9) for all three sam ples (Ta bles 1, 2). The two min er al ized vein sam ples that con tain ti tan ite were an - a lyzed in three (MMI ) or four (MMI ) frac - tions. An a lyt i cal re sults from the frac tions can be in ter - preted in two ways. If the data from the two widely sep a rated cop per sul phide epidote K-feld spar-ti tan ite veins are part of the same min er al iz ing event, then the data may be con sid ered col lec tively, in which case a pooled con - cordia age for the two dated ti tan ite sam ples yields ±0.6 Ma (mean square of weighted de vi ates [MSWD] = 1.16, prob a bil ity = 0.28). How ever, we pre fer the more con - ser va tive ap proach, and con sider the age of the min er al iz - ing event as some time(s) be tween the 2 error envelopes of Ma. Four sin gle zir con frac tions were an a lyzed from the Mine Dyke sam ple. Er ror en ve lopes for the in di vid ual anal y ses mu tu ally over lap on con cordia. To gether they pro - vid ing a tight age de ter mi na tion of ±0.25 Ma, with a MSWD of 1.8 and prob a bil ity of con cor dance of 0.18 (Fig - ure 9). We rec om mend us ing a slightly more con ser va tive best age of 103 ±0.3 Ma. 40 AR/ 39 AR COOLING AGE The 40 Ar/ 39 Ar iso to pic age de ter mi na tions were ob - tained by the la ser-in duced step-heat ing tech nique. De tails of the an a lyt i cal tech niques are pre sented in Lo gan et al. (2007). Gas mea sure ments ob tained dur ing each of the heat ing steps are pre sented in Ta ble 3. Con sid er ation of the en tire re lease spec trum pro duces a to tal re lease in te grated age of ±0.95 Ma (Ta ble 3), which is not geo log i cally mean ing ful. Low-tem per a ture steps should be re jected (Fig ure 10) be cause loosely bound ar gon has been par tially lost. A re sul tant, ro bust pla teau pro duced by the highertem per a ture steps 8 through 14 rep re sents 71.8% of the Fig ure 4. Geo log i cal timeline show ing age de ter mi na tions from the min er al iz ing sys tem at Cop per Moun tain, south-cen tral Brit ish Co lum bia. Tri as sic-ju ras sic bound aries from time scales dis - cussed in the text are H = Harland et al. (1982), J = Pálfy et al. (2000) and K = Kulp (1961). Ab bre vi a tions: H, Hettangian; P, Pliensbachian; R, Rhaetian; S, Sinemurian; T, Toarcian. Time scale is from Okulitch (2002), which in cor po rates the Ju ras sic time scale of Pálfy et al. (2000). 39 Ar re leased. This pla teau pro vides the best in ter preted age of ±1.1 Ma (1, in clud ing J-er ror of 0.5%). The MSWD for this de ter mi na tion is 0.29, with a prob a bil ity of Ini tial 40 Ar/ 36 Ar is 277.6, lower than the at mo spheric value of DISCUSSION OF AGE DETERMINATIONS Ex ten sive in tru sion of the Cop per Moun tain area by the swarm of Mine Dykes has re set the iso to pic sys tems with low clo sure tem per a tures. For ex am ple, fis sion-track cool ing ages for the Lost Horse In tru sions and dikes are re - ported by Chris to pher (1973) as rang ing from 100 to 127 Ma (with un cer tain ties on the or der of ±25 Ma see Fig ure 3 for spe cific ex am ples). These dates re flect the an - neal ing of ap a tite within the Late Tri as sic in tru sions where they are in ter sected by the dike swarm. The U-Pb age re - ported herein, ± 0.3 Ma, is the first crys tal li za tion age from the Mine Dyke swarm, and is con cor dant with the fis sion track ages. It is iden ti cal, within er ror, to the age of the Verde Creek quartz monzonite, which is dated by K-Ar bi o tite as 100 ±8 Ma and 102 ±8 Ma (Breitsprecher and Mortensen, 2004; re cal cu lated from Preto, 1972 as British Columbia Geological Survey

5 ±4 Ma and 101 ±4 Ma).The Mine Dykes, however, are observed to cut the Verde Creek pluton (Preto, 1972) and must, at least locally, be younger. Interestingly, the northerly trending dike swarm parallels the straight western margin of the 20 km long Verde Creek pluton, which is located immediately east of the area outlined by the southern half of Figure 2. Isotopic age determination of mineralization at Copper Mountain has relied largely upon cooling ages or imprecise fission track techniques (Figures 3, 4). Although a robust U-Pb zircon age from the Copper Mountain stock yielded / 0.5 Ma, ±2.1 Ma and 204 ±6 Ma (Figure 4; Mortensen et al., 1995), age determinations from mineralization have historically been by techniques susceptible to isotopic disturbance. This is particularly problematic in the mine area where extensive intrusion by the younger Mine Dykes heated the surrounding country rocks. Such cooling ages include K-Ar biotite determinations on the Copper Mountain stock and mineralized veins that yielded a mean age of 193 ±7 Ma (Sinclair and White, 1968), and those on the pegmatitic sulphide veins and Lost Horse and other intrusions that yielded a mean age of ±8 Ma (Preto, 1972). Consistency of these two datasets and the time scale calibration of the day (Kulp, 1961) placed the intrusions and mineralization within the Figure 5. Light-coloured Mine Dykes cutting dark, hydrothermally altered Nicola Group volcanic strata within Pit 3, Copper Mountain, south-central British Columbia. View is to the southeast. The location of sample MMI is just visible on the far pit wall (red arrow). Figure 6. Pegmatitic mineralized K-feldspar veins containing copper carbonate stained biotite chal copyrite bornite epidote titanite, Copper Mountain, south-central British Columbia. The light-coloured halo is probably due to albite alteration. Geological Fieldwork 2009, Paper Figure 7. Titanite grains an alyzed from samples from Copper Mountain, south-central British Columbia: A) titanite from sample MMI ; field of view is ~2 mm; B) titanite from sample MMI0632-5; field of view is ~2 mm; C) zircon separate from sample MMI prior to abrasion (200 mm scale bar). 167

6 168 Table 1. U-Pb thermal ionization mass spectrometry analytical data for titanite from mineralized veins in samples MMI and MMI , Copper Mountain, south-central British Columbia. Table 2. U-Pb thermal ionization mass spectrometry analytical data for zircon from the Mine Dyke sample MMI , Copper Mountain, south-central British Columbia. British Columbia Geological Survey

7 Late Tri as sic pe riod, which ex tended to 181 Ma (K on Fig - ure 4). Both the min er al ized veins and in tru sions cut rocks that con tain mea gre but sig nif i cant fos sil col lec tions yield - ing Late Tri as sic ages. Penecontemporaneous coun try rocks and in tru sions seemed con sis tent with ev i dence for a near-sur face in tru sive en vi ron ment Such ev i dence includes por phy ritic tex tures and brec cia bod ies in dic a tive of low con fin ing pres sures (Preto, 1972). How ever, a time scale re vi sion in 1982 (Harland et al., 1982; H on Fig ure 4) pushed the Tri as sic-ju ras sic bound ary back to 208 Ma, pro - vid ing for a ~15 m.y. lag be tween de po si tion of arc strata and in tru sion. A sub se quent re vi sion of the Ju ras sic time scale for the Ca na dian Cor dil lera (Pálfy et al., 2000; J on Fig ure 4), mod er ated the 1982 Tri as sic-ju ras sic bound ary re vi sion, plac ing the new bound ary at 200 ±1.0 Ma. Fol - low ing the time scale re vi sion in 2000, the Cop per Moun - tain story was: in tru sion around 202 Ma, in the Late Tri as - sic, fol lowed by min er al iza tion around 193 Ma, in the Early Ju ras sic. In light of typ i cal du ra tions for hypogene ore for - ma tion, which range from 0.01 to 0.1 m.y. for Cu±Mo±Au por phyry de pos its worldwide (McInnis et al., 2005) the lag time of nearly 10 m.y. seemed unreasonable, and most Fig ure 9. Con cordia plot for U-Pb ther mal ion iza tion mass spec - trom e try data for the Mine Dyke sam ple, MMI , Cop per Moun tain, south-cen tral Brit ish Co lum bia. 2 er ror el lip ses for in di - vid ual an a lyt i cal frac tions are in red. The blue el lipse rep re sents the best es ti mate con cordia age of the sam ple. Con cordia bands in clude 2 er rors on U de cay con stants. Fig ure 8. Con cordia plots for U-Pb ther mal ion iza tion mass spec - trom e try data for sam ples from Cop per Moun tain, south-cen tral Brit ish Co lum bia: A) sam ple MMI ; B) sam ple MMI er ror el lip ses for in di vid ual an a lyt i cal frac tions are red. Blue el - lip ses rep re sent the best es ti mate con cordia age of the sam ple. Con cordia bands in clude 2 errors on U de cay con stants. Fig ure 10. Step-heat ing Ar gas re lease spec tra for euhedral bi o tite from sam ple MMI , Big Lead, bornite-bi o tite ore, Cop per Moun tain, south-cen tral Brit ish Co lum bia. Pla teau steps are filled; re jected steps are open. Box heights at each step are 1. Ris ing low-tem per a ture steps to the ro bust pla teau at ±1.1 Ma in di - cate a def i cit of loosely bound Ar. Geo log i cal Field work 2009, Pa per

8 Table Ar/ 39 Ar step heating gas release data from sample MMI , a centimetre-thick slice of a sample of the Big Lead glory hole biotite-bornite mineralization, Copper Mountain, south-central British Columbia. likely attributable to the large errors of the age determinations from min er al iza tion (Figure 4). Our sam pling of min er al iza tion in cludes ti tan ite-bi o - tite bear ing veins in the mar gin of the Cop per Moun tain stock and those equi dis tant be tween the Cop per Moun tain stock and the body of Lost Horse In tru sions (Fig ure 3). In ad di tion to this spa tial vari abil ity, we have used two dif fer - ent tech niques: U-Pb ti tan ite and 40 Ar/ 39 Ar bi o tite dat ing with clo sure tem per a tures of C (Scott and St- Onge, 1995) and C (McDougall and Har ri son, 1999), re spec tively. These tech niques are more ro bust than the K-Ar bi o tite tech nique used in the past. Our re sults for the ti tan ite-bear ing veins, ±1.0 Ma and ±0.7 Ma, are iden ti cal, within er ror, to the crys tal li za tion ages re ported by Mortensen et al. (1995). If there is any sys - tem atic dif fer ence in the ages of in tru sion and min er al iza - tion, its mea sure ment is be yond the res o lu tion of the geochronometers avail able to us. This contemporaneity of in tru sion and hypogene min er al iza tion is con sis tent with the re sults of sim i larly ro bust datasets else where within the Cordilleran belt of alkalic por phyry de pos its (e.g., Iron Mask and Mt. Polley; Lo gan et al., 2007), and re sults from other por phyry sys tems glob ally (McInnis et al., 2005). Our new data pro vide a tight in te gra tion of the Cop per Moun - tain de posit with the ca Ma alkalic Cu-Au porphyry event that stretches the length of the Canadian Cordillera. ACKNOWLEDGMENTS T. Ullrich con ducted and in ter preted the 40 Ar/ 39 Ar anal y ses. H. Lin car ried out min eral sep a ra tions and pro - vided as sis tance with mass spec trom e try; R. Lishansky as - sisted with grain se lec tion, abra sion and in the clean lab. G. Nixon pro vided dig i tal data from Geoscience Map to aid con struc tion of Fig ures 2 and 3. Ac cess to the pits at Cop per Moun tain was granted by J. Cul len of Envirogreen Tech nol o gies Ltd. An ear lier draft of this manu script was reviewed by S. Rowins. REFERENCES Ash, C.H., Reynolds, P.H., Creaser, R.A. and Mihalynuk, M.G. (2007): 40 Ar/ 39 Ar and Re-Os iso to pic ages for hy dro ther mal al ter ation and re lated min er al iza tion at the High land Val ley Cu-Mo de posit (NTS 092I), south west ern Brit ish Co lum bia, in Geo log i cal Field work 2006, BC Min is try of En ergy, Mines and Pe tro leum Re sources, Paper , pages Barger, H. and Schurr, S. (1944): The min ing in dus tries, : a study of out put, em ploy ment, and pro duc tiv ity; The Na tional Bu reau of Eco nomic Re search, Publication Number 43, 447 pages. BC Geo log i cal Sur vey (2009): MINFILE BC min eral de pos its da - ta base; BC Min is try of En ergy, Mines and Pe tro leum Re - sources, URL < [De cem ber 2009]. Breitsprecher, K. and Mortensen, J.K. (2004): BC Age 2004A-1: a data base of iso to pic age de ter mi na tions for rock units from British Columbia; BC Min is try of En ergy, Mines and Pe tro - leum Re sources, Open File Brown, D.A., Gun ning M.H. and Greig, C.J. (1996): The Stikine Pro ject: ge ol ogy of west ern Tele graph Creek map area, northwestern British Columbia (104G/5, 6, 11W, 12 and 13), BC Min is try of En ergy, Mines and Pe tro leum Re sources, Bul le tin 95, 176 pages. Chance, A.V., Giroux, G.H., Holbek, P.M., Mar tin, T., Murray, D., O Rourke, J.C., El Sabbagh, M. and Thomp son, I.S. (2009): Tech ni cal re port on the Cop per Moun tain Pro ject, Prince - ton, British Columbia; Copper Mountain Mining Corp. Chris to pher, P.A. (1973): Ap pli ca tion of K-Ar and fis sion track dat ing to the metallogeny of por phyry and re lated min eral deposits in the Canadian Cordillera; Canadian Journal of Earth Sci ences, Vol ume 10, pages British Columbia Geological Survey

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